CVE-2026-64123 Linux CVE debrief

Who should care

Linux kernel users and administrators should be aware of this vulnerability and take steps to ensure their systems are updated with the patched kernel. This includes reviewing system configurations, monitoring system logs for potential exploitation attempts, and ensuring that HSR is properly configured.

Technical summary

The vulnerability was caused by the HSR node-list and node-status generic-netlink operations running under rcu_read_lock() and holding a struct hsr_node pointer across hsr_dellink(). This led to a slab-use-after-free when the reader copied node->macaddress_A. The issue was resolved by changing the node deletion to use list_del_rcu() and deferring the free through the existing hsr_free_node_rcu() callback. This change ensures that the node table is not freed until after RCU readers have completed, preventing the use-after-free vulnerability.

Defensive priority

High

Recommended defensive actions

• Update the Linux kernel to the patched version
• Review system configurations and ensure HSR is properly configured
• Monitor system logs for potential exploitation attempts
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record was published on 2026-07-19T16:17:53.907Z and has not been modified since then. The NVD entry is currently Received. There is no additional information available about the vulnerability beyond what is provided in the CVE record and NVD entry.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.